Membranes composed of Polymers of Intrinsic Microporosity (SBF-PIMs) have potential for commercial gas separation. Here we report a combined simulation and experimental study to investigate the effect on polymer microporosity and gas permeability by placing simple substituents such as methyl, t-butyl and fused benzo groups onto PIMs derived from spirobifluorene (PIM-SBFs). It is shown that methyl or t-butyl substituents both cause a large increase in gas permeabilities with four methyl groups enhancing the concentration of ultramicropores (<0.7 nm), which contribute to selective gas transport. The t-butyl substituents lower selectivity by generating a greater concentration of larger, less selective, micropores (>1.0 nm). Long-term ageing studies (>3.5 years) demonstrate the potential of PIM-SBFs as high-performance membrane materials for gas separations. In particular, the data for the PIM derived from tetramethyl substituted SBF reaches the proposed 2015 Robeson upper bound for O₂/N₂ and, hence, hold promise for the oxygen or nitrogen enrichment of air. Mixed gas permeation measurements for CO₂/CH₄ of the aged PIM-SBFs also demonstrate their potential for natural gas or biogas upgrading.

中文翻译：

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具有固有微孔性的高选择性螺二芴基聚合物的合成，链堆积模拟和长期气体渗透性†

由内在微孔性聚合物（SBF-PIMs）组成的膜具有用于工业气体分离的潜力。在这里，我们报告了一个组合的模拟和实验研究，以通过将简单的取代基（例如甲基，叔丁基和稠合的苯并）放置在衍生自螺二芴（PIM-SBFs）的PIM上来研究对聚合物微孔率和气体渗透性的影响。已显示甲基或叔丁基取代基均引起气体渗透率的大幅增加，其中四个甲基增强了超微孔的浓度（<0.7 nm），这有助于选择性的气体传输。该Ť丁基取代基会产生较大浓度的较大，选择性较低的微孔（> 1.0 nm），从而降低选择性。长期老化研究（> 3.5年）证明了PIM-SBFs作为用于气体分离的高性能膜材料的潜力。尤其是，源自四甲基取代的SBF的PIM数据达到了拟议的2015年Robeson上限O ₂ / N ₂，因此对于空气中氧气或氮气的富集具有希望。老化的PIM-SBF的CO ₂ / CH ₄的混合气体渗透率测量结果也显示出其天然气或沼气升级的潜力。